Urbanization can be Beneficial for Orb-weaving Spiders, Study Finds

A common orb-weaving spider may grow larger and have an increased ability to reproduce when living in urban areas, according to a study published recently in the journal PLOS ONE.

Urbanization of an area may drastically alter the landscape, local climate, and consequently the organisms that inhabit it. Some will no longer have the resources they need to survive in the urban environment, while others may thrive, possibly more so than in their native habitat. One way in which this may be evident is in marked changes in the organism’s size.

The authors of this particular study investigated changes in the physical attributes of Nephila plumipes, an orb-weaving spider commonly found in both urban and natural landscapes. The researchers quantified the degree of urbanization at multiple sites in Sydney, Australia, and investigated changes in the orb-weaving spider’s body size, fat reserves, and ovary weight.

Results show that the spiders had smaller bodies in non-urban areas with more vegetation cover, and larger bodies in areas associated with urban development, indicated by the presence of hard surfaces. Additionally, the authors found that the spiders’ reproductive ability, measured by increased ovary weight, may have increased in areas with hard surfaces.

“Our study shows that N. plumipes is an urban exploiter,” the authors wrote.

According to the researchers, the larger size and increased reproductive capacity of orb-weaving spiders in urban areas further support the idea that some species may benefit from habitat changes associated with urbanization.

“Our results show support for our first hypothesis that urbanization has a positive effect on N. plumipes body size and ovary weight at multiple landscape scales,” the authors wrote. “Spider size increased with hard surface cover at a local and microhabitat scale and decreased in areas with more vegetation cover. Spider ovaries were significantly larger in sites in close to the city, and in areas with more hard surfaces and less leaf litter.”